Who

Britney Spears & Kevin Federline

After Britney Spears' 55-hour marriage to Jason Alexander, the singer -- then 22 -- got engaged to Kevin Federline in July 2004. On November 7, 2006, Spears filed for divorce from Federline, citing irreconcilable differences.

Photo by Getty Images Jun 6, 2012

Engaged & Underage!

Cyrus isn’t the first — or the last — baby bride in Hollywood. She joins a long list of female celebs who’ve tied the knot young.